Mysticeti refers to the baleen whales - whales that have a filtering system (made up of baleen plates) hanging from their upper jaw. The baleen filters the whale's food from the ocean water.
The taxonomic group Mysticeti is a suborder of the Order Cetacea, which includes all the whales, dolphins and porpoises. These animals may be referred to as mysticetes, or baleen whales. Some of the largest animals in the world are mysticetes.